This invention relates generally to injection molding and more particularly to apparatus for locating and sealing an injection molding nozzle in an opening in the mold.
Very accurate location of a heated nozzle in an opening in a cooled mold has become more and more critical for successful hot tip gating. As seen in the applicant's U.S. Pat. No. 4,557,685 which issued Dec. 10, 1985 and U.S. Pat. No. 4,768,945 to Schmidt et al. which issued Sep. 6, 1988 it is well known for heated injection molding nozzles used for hot tip gating to have a rear locating flange and a front seal extending therearound. Another example of hot tip gating is shown in U.S. Pat. No. 5,658,604 to Gellert et al. which issued Aug. 19, 1997 in which the front seal is provided by a threaded nozzle seal which is screwed into the front end of the nozzle.
U.S. Pat. No. 4,771,534 to Gellert et al. shows a nozzle with a sealing and locating flange but it does not abut against an inwardly tapered surface. U.S. Pat. No. 5,269,676 shows a seating and sealing insert, but it does not have an inwardly tapered surface against which a locating and sealing ring can seat.
However, the previous apparatus all has the disadvantage that extremely close tolerances are required to ensure the front end of the nozzle is accurately aligned and there is a good seal against melt leakage.